Joseph Parker's camp have again fired shots at British champion heavyweight Anthony Joshua ahead of their unification bout, saying Joshua's muscular frame will be his weakness.

Parker's trainer Kevin Barry says the new and technical training regimes Joshua is doing in his training camp will not help with his aerobic fitness.

"I see videos posted everywhere of him (Joshua) doing the most sophisticated, new age training methods that man has ever seen and yet he's looked very tired in his last couple of fights," Barry told Sky Sports UK.

Every time he's been asked to go on to the later rounds, he's really struggled - Joseph Parker's trainer Kevin Barry

"Every time he's been asked to go on to the later rounds, he's really struggled so that's a question for his training staff.

Over 70,000 tickets have been sold for the epic unification bout on April 1 (NZ time) in Cardiff.
Source: 1 NEWS

"He wouldn't want to be slowing against Joe, because I can promise you this. Joe will be coming on in the later rounds."

Parker is currently in Las Vegas training ahead of his bout with Joshua on April 1 (NZ time).

The Kiwi WBO heavyweight champ said even though he is not as muscular as his opponent, he will be ready to go the distance in their 12 round unification fight.

"My body type even though it's not really muscular, (has) worked for us. We know that we can fight hard from round one to 12. It's all that matters," Parker told Sky Sports UK.